Mercruiser Fuel Pressure Diagnostics

Рет қаралды 24,598

Жыл бұрын

We’ve been having running issues with our 2006 341 Meridian’s Mercruiser 6.2 motors. Our port motor won’t go over 4000rpm. Follow along as we diagnose the problem by first checking the fuel pressure on the two motors using a fuel pressure gauge and comparing the readings to hopefully troubleshoot our problem and fix the issue of low rpm on one engine.
Product links:
Fuel pressure gauge: amzn.to/3VpLq5C

Пікірлер: 53

@alexjullien9508 Жыл бұрын

Great video, thanks for sharing, good to see how to and the resuilts of fuel pressure testing - thanks!!!

@sousasons1891 Жыл бұрын

Been a follower of your trip. Love the vids! Question, how long was your actual journey from NY to when you landed in Cape Coral?

@AdventuresofHappyOurs Жыл бұрын

We left upstate NY June 30 and arrived Cape Coral August 2. But we stopped every so often to enjoy the roses so to speak.

@allendabold5611 Жыл бұрын

I had that same problem and I had a bad alternator belt and was a low voltage issue

@anthonycaffarini5687 Жыл бұрын

Hey, mercuiser tech here, I noticed in an earlier video that you have the gloss black fuel pressure regulator caps. Those are notorious for paint delaminating inside them and clogging the injectors. Your 50 psi at key up is too high. Max should be 42. If you pull off the fuel pressure regulator, the silver round thing on top of the fuel pump, and see paint. You have the problem. If you have a Merc dealer perform the repair you get the parts for free, all you do is pay the labor. Hope this helps.

@AdventuresofHappyOurs Жыл бұрын

I’ll be pulling the cap in a future video. Wouldn’t 50psi when ignition first turned on normal as there is no vacuum until start? What pressure should I get with vac hose removed from regulator?

@anthonycaffarini5687 Жыл бұрын

@@AdventuresofHappyOurs There is no vacuum no, but there is a mechanical spring in the regulator that alleviates pressure as well. Keep in mind the fuel rail is totally depressurized and the pump only runs for 3 secs at key up. On a healthy system, If you key on and key off multiple times, you’ll notice the pressure just levels off to a point. It wont keep building. A test for the regulator would be to hook up your pressure gauge again and pull the tiny hose coming off the regulator. It should spike up 3-4 psi once removed. It should be around 44-45 with it removed. If it goes up to around 50 removed, you definitely have paint in the fuel. If it doesn’t move at all the regulator is either ruptured or there’s a hole in the vacuum line.

@AdventuresofHappyOurs Жыл бұрын

Thanks! I’ll try pulling the vac line while running next time out

@seconnsportsman2502 Жыл бұрын

Spot on Anthony. The good news is the gauge didn’t peg at idle, which as you know means the injectors are not (yet) clogged by paint flakes from the CFM3

@jamesbaker7287 Жыл бұрын

@anthonycaffarini5687 , hey, I see that you're a mercruiser tech and was wondering if you'd be able to help or point me in the right direction with an issue I'm having with my 2002 bayliner capri, 4.3l mpi mercruiser. It'd be kind of long to write/explain it on here so if possible, could you maybe respond on here and I'll give you my email address or something? I know it's a lot to ask coming from a stranger, but I'd really appreciate it.

@kasperwittrup1288 Жыл бұрын

Could also be one or two of the injectors on the engine thats clogged. Had the same on mine (outboard). It would run fine without load with earmuff's on, but when putting it under load in the water, I couldent get it higher than 2200 rpm. Cleaning the injectors fixed the issue. Also checked all filters, sparkplugs and pumps - some were a little dirty from regular use, but once I fixed the injectors - all problems went away. Is the engine running rough under pressure when you give it full throttle? That could mean its not firing on all cylenders - thats what mine did.

@AdventuresofHappyOurs Жыл бұрын

It’s running smooth just not getting to max rpm. I’ll be methodically checking and testing each step. Stay tuned!

@macgyvernetwork1437 Жыл бұрын

Do a tune up. Plugs, wires, cap, rotor and coil. Make sure to replace the cap and rotor with the high performance gold plated points cap, they work a lot better than the silver point caps. I would also upgrade the ignition coil with a high performance, msd coil, accell coil… replace these on both engines. You will be so much happier!

@macgyvernetwork1437 Жыл бұрын

Beautiful boat by the way!

@MrStangdawg Жыл бұрын

MSD is the worst coil EVER. MSD = My Shitty Day

@frednageljr9809 Жыл бұрын

I have a 36 ft caver seadan bridge with your same issues. replaced the plugs first.;no change.It ended up being a bad injector replaced all off the injectors , boat runs perfect.

@AdventuresofHappyOurs Жыл бұрын

I had a 2000 carver Mariner. Great boat.

@mchaves7663 Жыл бұрын

I may have the same issue.how hard is to replace the injectors? Do I need special tools?

@AdventuresofHappyOurs Жыл бұрын

The company that sent me the CFM said it is not hard. Just have to remove the fuel rail. I haven’t tackled that. I am eliminating all other possibilities first and will do a injector cleaning through the rail before attempting to remove them.

@mchaves7663 Жыл бұрын

@@AdventuresofHappyOurs hi Anthony, I pulled the fuel rail off this weekend. I tested the 8 injectors with a pipe and a carb spray can (see videos on this) and found 2 bad injectors that were leaking. They were stuck open. That's why it was hard to start my engine. If you do this, make a video. Haven't seen anybody doing that for mercruiser. Hope this helps you cheers

@AdventuresofHappyOurs Жыл бұрын

I plan to do that tomorrow n the future. So much work ahead. Thanks.

@Blehahib Жыл бұрын

This is a manifold vacuum based fuel system. RPM with no load makes it hard to determine if the fuel pressure is correct. The gauge might be air locked, so it might not be super accurate, but what you are looking for is when the regulator is unplugged it raises the pressure by about 7 psi. Because you compared the engines though, even though the gauge is inaccurate (maybe), it gives you a good baseline to say that most likely fuel is not yet your issue. The engines sound like they are idling way too low though. I would replace the IAC muffler to fix that.

@AdventuresofHappyOurs Жыл бұрын

IAC Mufflers we’re replaced early 2022. The motors didn’t get to warm up at all so may sound a little rough. But it seems to idle fine after a minute or so of fast idle. I’m thinking a simple tune up will do the trick. We’ll see.

@WhenPigsFlyHigh Жыл бұрын

Thanks….Definitely the plugs. You going to go ahead and change out both engines?

@AdventuresofHappyOurs Жыл бұрын

Yea sir! Stay tuned!

@seconnsportsman2502 Жыл бұрын

Those Horizons came from the factory with Iridium plugs. Can’t hurt to change them but that’s not causing the top end RPM loss. AC Rapid Fire #14 or AC/Nipp 41-993 Both are .060 gap. Use anti seize.

@WhenPigsFlyHigh Жыл бұрын

@@seconnsportsman2502 maybe you are correct. I’m not a mechanic in no way. My port side engine wouldn’t do anything past 3500 RPM and I had vibrations at idle speed. I had the plugs pulled and replaced. Vibrations are gone and my RPM’s are perfect.

@AdventuresofHappyOurs Жыл бұрын

I have the iridium’s ready to go in. Thank for gap!

@ralphmilroy6460 Жыл бұрын

Hi, I can only guess that your problem occurs at 4000 rpm with your engine under load. You only tested at idle, 1000 and 2000 rpm (sitting at the dock?). I'm not sure you replicated the flaw. Your Mercruiser has an ECM, not OBDII, compliant. There are other parameters I'd like to see/compare. You should do the compression test anyway just to benchmark your engines. 16 spark plugs wouldn't be a bad idea either.

@kkeane5749 Жыл бұрын

Pull the plugs and check for rust due to water intrusion especially on the center cylinders. If there's rust then do a compression test. Mercruisers are famous for this and it will take out the valves and valve seats resulting in no compression. If theyre fine it can be just a tune up or a bad fuel injector

@AdventuresofHappyOurs Жыл бұрын

I’ll keep you updated. I have all tuneup parts ready. Just need time now! Lol

@seweryngralak8064 7 ай бұрын

good afternoon . Have you finally found the cause of this problem? I have the same situation and I don't know what is the cause. Please let me know. Greetings from the Netherlands :)

@AdventuresofHappyOurs 7 ай бұрын

The 150 rpm difference between motors is still a mystery but it be heard 100 to 200 rpm difference between motors is not uncommon. The next major step is to have the injectors cleaned.

@jeffpiper7147 Жыл бұрын

I had a similar problem believe it or not it was that the fire arrester was dirty restricting are intake it’s an easy fix

@AdventuresofHappyOurs Жыл бұрын

I cleaned mine the year before. They don’t get that dirty.

@jeffpiper7147 Жыл бұрын

I did complete tune up changed fuel pump changed water separator more than once. I didn’t realize the marina didn’t clean the fire arrestor when they winterized the motors. I do have four barrel carbs so maybe a little different but it was the problem ran great at idle but under a load it choked out so just a suggestion good luck and don’t let everybody make you crazy sometimes you need a professional in Connecticut they aren’t cheap

@LarryKatz Жыл бұрын

I would start by inspecting the plug wires. One way to inspect is to start the engine in the pitch black with no interior lighting and without getting tangled in the running engine look for blue light emitting from any wires as they leave the distributor cap all the way to the plugs. My guess is wires! It wouldn’t hurt to tune and replace wires as regular maintenance.

@AdventuresofHappyOurs Жыл бұрын

They’ve been replaced. That vid coming.

@davidkolbasky8066 10 ай бұрын

Ever figure out this issue?

@AdventuresofHappyOurs 10 ай бұрын

Yep. That story coming soon.

@jimwalton7271 8 ай бұрын

@@AdventuresofHappyOurs Did you post "The Rest of the Story" yet? ;-) Different boat, but same 4k max RPM issue (even with all new plugs, wires, cap, rotor, gas, bottom paint, clean injectors etc but original 07 cool fuel module). thx

@AdventuresofHappyOurs 8 ай бұрын

@jimwalton7271 after lots of diagnostics not finding issues and consulting with many others, consensus is a hundred or so rpm difference between motors is acceptable, especially for17 year old motors.

@jimwalton7271 7 ай бұрын

Thx for the clarification. However, I thought the issues was 4k rpm limit vs 4800 to 5200 rpm spec limit for the 6.2L engine itself? Appreciate all the time you took to record and post your videos.

@lou_chicago Жыл бұрын

Most likely your spark plugs. :)

@AdventuresofHappyOurs Жыл бұрын

Got those new iridium plugs ready to go!

@lou_chicago Жыл бұрын

@@AdventuresofHappyOurs BTW, Happy to see you made it thru IAN. Love the channel.

@cliffcrowley3756 Жыл бұрын

Come on Goomba! You have a $12 Chinese pressure gauge. Stop shopping at Harbor Freight! I would replace the rotor, Dist cap, plugs as normal maintenance after that long trip and maybe they are due anyway. And go out and buy a $14 Chinese compression gauge and check compression on the lazy engine. Ihave 5.7 MPI Horizon I think they suggest changing the rotor and cap every 2 years and you put alot of hours on this year.

@AdventuresofHappyOurs Жыл бұрын

All the parts are in. Hopefully get all that changed out by this weekend.